Process of desulphurizing gold and silver ores



(No Model.) 2 Sheets-Sheet 1. J. H. MATHEWS.

PROCESS OF DESULPHURIZING GOLD AND SILVER ORES. No. 334,961.

Patented Jan. 26, 1886.

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J. H. MATHEWS.

PROCESS OF DBSULPHURIZI'NG GOLD AND SILVER 035%.

No. 334,961. Patented Jan. 26, 1886.

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JOSEPH H. MATHEWS, OF CANTON, OHIO.

PROCESS OF DESULPHURIZING GOLD AND SILVER ORES.

$PIQCIFICATION forming part of Letters'Patent No. 334,961, dated January 26, 1886.

Application filed November 12, 1884. Serial No. 147,717. (No model.)

To all whom it may concern.-

of Canton, in the county of Stark and State of Ohio,have invented certain new and useful Im provements in a Process of Desulphurizing Gold and Silver Ores; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same.

Myinvention relates to an improved process of desulphurizing gold and silver ores; and it consists, essentially, in. heating in closed vessels pulverized ores to within given limited degrees of heat, and treating the heated ore to the action of superheated steam under pressure, but preferably limited within a definite range of pressure, to the end that all the met als in the ore, except gold and silver, are

quickly and cheaply oxidized and the gold and silver are left in a free metallic state and in proper condition for amalgamation.

lVith these objects in view my invention consists in a process, the different steps of which are hereinafter described, and pointed out in the claims.

A suitable apparatus for carrying out my invention is illustrated in the accompanying drawings. I

Figure 1 is an end elevation of the apparatus. Fig. 2 is a transverse vertical section of the same. Fig. 3 is a side elevation of the cylinder, a portion of which is broken away to show the central tube inside with the walls of the setting in vertical section. Fig. 4 is a plan view of the furnace, flue, and heating chamber, showing a plan of the cylinder with portions broken away and a horizontal section of the central tube below. Fig. 5 is a longitudinal section of a portion of the central tube and a transverse section of the packing-rings, diaphragm, and a portion of the attached cylinderhcad.

A represents a horizontal closed cylinder, provided with suitable doors for access to the inside, and mounted on rollers a, and provided with any suitable mechanism for revolving the cylinder, and has inside longitudinal ribs, a, for elevating the ore. Through the center of the cylinder passes longitudinally the steam pipe B, that is divided inside by the diagonal partition B into two compartments, each ex- Be it known that I, JosEPH H. MATHEWS,

tending about the length of the cylinder, as shown in Fig. 4, by means of which the pipe B serves as an induction and eduction tube. On the induction side the tube B is provided with a number of short nozzles, b, that direct the steam entering the cylinder laterally toward the upper portion of the ore L, that is piled to the one side by the rotation of the cylinder. The eduction side of the tube is provided with nozzles b, reaching near the bottom of the cylinder and opening from the ore, as shown in Fig. 2.

0 represents a firebox, provided in the usual manner with grates, doors, &c., and connects above with the flue D,tl1at leads laterally into the heatingchamber F, that partially surrounds the cylinder. A- fine, D, leads from the rear of the furnace to the chimney G, and is provided with the damper d. A coil of pipe, E, is connected with any suitable steamgenerator, and is located in the upper portion ofthe fire-box O and in the flue D, and passed out in front, and is joined to the tube B, and is provided with the valve E,to control the admission of steam to the cylinder. The pipeB at the rear is provided with the valve H, connecting it with the tube H, leading to the chimney, and has a sliding door, h,through which the escaping gases may be inspected. The lower part of the chamber F is more or less obstructed by the piers f, so that the products of combustion are retarded in their passage and made to fill the chamber and equalize the heat therein. The lower part of this chamber connects at the rear with the flue K, leading to the chimney G. A preferable way of making a tight joint between the head of the cylinder and the tube 13 is shown in Fig. 5. The head of the cylinder A is cut away some distance from the tube, and has attached a thin metal dia phragm, I, to which is secured a friction-ring, t, that loosely encircles the tube. This ring abuts against the collar J, that fits the tube B, making a tight joint. The pressure of steam from the inside keeps the ring z tight against the collar J, and prevents the escape of steam from the cylinder.

In carrying out my process a suitable quan; tity of pulverized ore is placed in the cylinder, and the latter is slowly revolved, while,

by means of the furnace, the pipes E and the steam therein and the cylinder and contents are heated. At first steam is allowed to pass through the cylinder toexpel the air, after which, by means of the valves E and H, the ingress and egress of the steam is controlled, so as to give the required pressure of steam in the cylinder. Meantime, as the ore becomes heated to about 400 Fahrenheit, the oxidation of the baser metals commences. The ores that are best adapted to be treated by this process usually contain considerable sulphur, that, especially when heated, has a strong affinity for the hydrogen contained in the superheated steam, with which it readily combines, forming sulphureted hydrogen, and the oxygen unites and forms oxides with the baser metals,

the gangues of which are found to be in the most favorable condition for the said oxidation when the ores are heated to from 400 to 650 Fahrenheit, but with a preferable mean temperature of from 500 to 550. Below 400, practically, oxidation does not commence, and above 650 combinations are formed with the gold and silver that are very difficult to amalgamate. In fact, above 650 the results are so different that it can hardly be considered the same process. A preferable range of heat is, as aforesaid, from 500 to 550. It is preferable in carrying out my process to keep the temperature below 600--the limit at which the compounds are most easily decomposed. Above 600 some of the ores will become mechanically coated by vitrified gangue, thus stopping the chemical action, and, further,

' making the amalgamation of a large part of the gold and silver extremely long and difficult, if not impossible. In addition to superheating the steam, some pressure is required to force the steam into close relation with the ore and cause it to penetrate deeper into the mass, and also to force the heavy sulphuretedhydrogen gas out through the said discharging'nozzle. It is found that usually from ten to fifteen pounds pressure of steam per squareinch is all that is required for these purposes. If it is found that the ores being treateddo not contain a sufficient amount of sulphur to unite with the hydrogen when such a decomposition of steam is had as will furnish the required amount of oxygen, the deficiency in sulphur may usually be supplied at small cost by adding pulverized iron pyrites. By tumbling the ores in the cylinder, portions of the ore, properly heated by contact with the slowly-ascending hot side of the cylinder, are in quick succession exposed to the action of the steam, resulting in a speedy and thorough treatment of the mass. The greater gravity of the sulphureted-hydrogen gas, as compared with steam, causes it to descend t0 the bottom of the cylinder, from whence it is expelled by the pressure -of steam above through the discharging-nozzle. WVhen there is no more sulphureted hydrogen given I off, which condition will be determined by chemical tests applied through the opening of the door It, such tests being well known to those skilled in the art, the oxidation will be complete. Tue heat is next shut off and the ore afterward removed for amalgamation. Meantime jets of steam or other means may be employed to cool the ore, so that it may be conveniently removed from the cylinder to make room for a fresh charge.

In my Patent No. 313,748 I describe the process of treating ores in a closed vessel to degrees of heat ranging from 600 to l,200. I therefore make no claim in this case to the high temperature therein described, but confine the process to degrees of heat herein described and claimed.

I am aware that argentiferous and auriferous ores have been roasted by introducing sup *rheated steam into a rotating cylinder in direct contact with the ores, and hence I make no broad claim thereto.

What I claim is- 1. The process of desulphnrizing and oxidizing the base metals of gold and silver ores, consisting, essentially, in heating the ore in a closed vessel to degrees of heat ranging from 400 to 600 Fahrenheit, and at the same time subjecting the ore to the action of superheated steam under pressure, substantially as set forth.

2. The process of desulphurizing and oxidizing the base metals of gold and silver ores, consisting, essentially, in heating the ore in a closed vessel to degrees of heat ranging from 400 to 600 Fahrenheit, and preferably within the range of from 500 to 550, and at the same time subjecting the ore to the action of superheated steam under pressure, substantially as set forth.

3. The process of desulphurizing and oxidizing the base metals of gold and silver ores, consisting, essentially, in heating the ore in a closed vessel to degrees of heat ranging from 400 to 600 Fahrenheit, and preferably within the range of from 500 to 550, and at the same time subjecting the ore to the action of superheated steam under a pressure ranging from ten to fifteen pounds per square inch, and tumbling or stirring the ores to expose all parts of the mass alike to the action of the steam, substantially as set forth.

4. The process of desulphurizing and oxidizing the base metals of gold and silver ores, consisting, essentially, in heating the ore in a 400 to 600 Fahrenheit, and at the same time subjecting the ore to the action of superheated steam under pressure, and stirring the ores to expose all parts thereof alike to the action of the steam, substantially as set forth.

JOSEPH H. MATHEWS. \Vitnesses:

JAMES J. GRANT, Vnnzo GRANT.

closed vessel to a temperature ranging from IIO 

